/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.instrument.classloading.websphere;

import java.lang.instrument.ClassFileTransformer;

import org.springframework.core.OverridingClassLoader;
import org.springframework.instrument.classloading.LoadTimeWeaver;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;

/**
 * {@link LoadTimeWeaver} implementation for WebSphere's instrumentable ClassLoader.
 * Compatible with WebSphere 7 as well as 8 and 9.
 *
 * @author Costin Leau
 * @since 3.1
 */
public class WebSphereLoadTimeWeaver implements LoadTimeWeaver {

    private final WebSphereClassLoaderAdapter classLoader;


    /**
     * Create a new instance of the {@link WebSphereLoadTimeWeaver} class using
     * the default {@link ClassLoader class loader}.
     *
     * @see org.springframework.util.ClassUtils#getDefaultClassLoader()
     */
    public WebSphereLoadTimeWeaver() {
        this(ClassUtils.getDefaultClassLoader());
    }

    /**
     * Create a new instance of the {@link WebSphereLoadTimeWeaver} class using
     * the supplied {@link ClassLoader}.
     *
     * @param classLoader the {@code ClassLoader} to delegate to for weaving
     */
    public WebSphereLoadTimeWeaver(@Nullable ClassLoader classLoader) {
        Assert.notNull(classLoader, "ClassLoader must not be null");
        this.classLoader = new WebSphereClassLoaderAdapter(classLoader);
    }


    @Override
    public void addTransformer(ClassFileTransformer transformer) {
        this.classLoader.addTransformer(transformer);
    }

    @Override
    public ClassLoader getInstrumentableClassLoader() {
        return this.classLoader.getClassLoader();
    }

    @Override
    public ClassLoader getThrowawayClassLoader() {
        return new OverridingClassLoader(this.classLoader.getClassLoader(),
                this.classLoader.getThrowawayClassLoader());
    }

}
